Sodium Electrode

ABSTRACT

A room temperature method and electrode for producing sodium metal in situ is disclosed. The electrode has a sodium hydroxide, or another easily electrolyzible sodium containing material, solution on the anode side, a membrane which permits sodium ions to pass through to the cathode where the sodium ions are reduced to sodium metal. This sodium metal is then available to react with other components of the solution on the cathode side.

RELATED APPLICATIONS

The present application claims benefit from earlier filed U.S.Provisional Application No. 61/793,897, filed Mar. 15, 2013, which isincorporated by reference in its entirety for all purposes.

BACKGROUND

1. Field of the Invention

The present disclosure is directed to a method and an electrode for theelectrochemical production of sodium at room temperature conditions.

2. Discussion of the Related Art

The production of sodium today is generally a byproduct of 0.2production using the well-know “Downs' cell” process which involves theelectrolysis of molten NaCl or a mixture of NaCl and CaCl2 heated to atleast 580 C.

Sodium is also used in many basic methods for drying and purifyingchemical solvents. Sonic other methods include distillation overmolecular sieves, distillation over inorganic salts and distillationover sodium, potassium or an amalgam of both.

In this last process, it should be noted that the sodium does not meltat the boiling point of many solvents, and thus, potassium is used toreduce the melting point of the amalgam. Although sodium reactsviolently with water, the exothermic reaction does not produce enoughenergy to auto-ignite any hydrogen present.

So clearly, a critical downside to the use of potassium is that theexothermic reaction of water and potassium produce enough energy toauto-ignite the resulting hydrogen if in the presence of oxygen. And,the presence of a flammable organic solvent poses an additional safetyhazard. This has been the cause of many laboratory accidents, whichcompels scientists to consider safer options. Another consideration ofacademic scientists is cost. Sodium and potassium compose the primarymaterial costs, while electricity is part of the general overhead.

For solvent purification, a small quantity of benzophenone is used. Thebenzophenone radical is created by the reduction of the benzophenone,and is an effective scavenger for water, oxygen, peroxides, and othercontaminants. It is also an indicator of the purity of the solvent. Atthe point when the concentration of the radical becomes stable insolution (the concentration of impurities has been reduced to ppmlevels), the solution takes on the deep blue-to-purple color of theradical, see reaction I below.

C₆H₅C=OC₆H₅+Na→Na⁺C₆H₅C=OC₆H₅ ⁻  I

A method to safely and reliably introduce alkali metal, particularlysodium metal, into various reaction schemes and/or solvent purificationschemes is of interest.

The presently disclosed electrochemical process utilizing a sodiumselective membrane and electrode can be utilized in numerousapplications and uses where sodium is produced, oxidized or exchanged asan ion.

The present application is directed to an electrode made up of a glasstube having an alkali metal-containing solution contained therein, aceramic membrane located at one end of the glass tube as an interfacebetween the alkali metal-containing solution and the outside solution,an anode located inside the glass tube and immersed in the alkalimetal-containing solution, and a cathode located. outside the glass tubeand immersed in the outside solution and electrically connected to theanode, wherein the ceramic membrane is permeable to alkali metal ions.

Also taught by the present disclosure is an electrochemical processcarried out by providing an electrode comprising a glass tube having analkali metal-containing solution contained therein, a ceramic membranelocated at one end of the glass tube as an interface between the alkalimetal-containing solution and the outside. solution, an anode locatedinside the glass tube and immersed in the alkali metal-containingsolution, a power source connected to the anode and cathode, and acathode located outside the glass tube and immersed in the outsidesolution and electrically connected to the anode, decomposing the alkalimetal in the alkali metal-containing solution to form alkali metal ions,passing the alkali metal ions through the ceramic membrane to theoutside solution, reducing the alkali metal ions to alkali metal at thecathode, and reacting the alkali metal with a reactant in the outsidesolution.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawing, which is included to provide a furtherunderstanding of the invention and is incorporated in and constitute apart of this specification, illustrates preferred embodiments of theinvention and together with the detailed description serve to explainthe principles of the invention. In the drawing:

FIG. 1 is a schematic illustration of the sodium electrode according tothe present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

According to the present disclosure, a room temperature method andelectrode for producing sodium metal in situ is disclosed. The electrodehas a sodium hydroxide (or another easily electrolyzible sodiumcontaining material) solution on the anode side, a membrane whichpermits sodium ions to pass through to the cathode where the sodium ionsare reduced to sodium metal. This sodium metal is then available toreact with other components of the solution on the cathode side.

The present application is directed to an electrode made up of a glasstube having an alkali metal-containing solution contained therein, aceramic membrane located at one end of the glass tube as an interfacebetween the alkali metal-containing solution and the outside solution,an anode located inside the glass tube and immersed in the alkalimetal-containing solution, and a cathode located outside the glass tubeand immersed in the outside solution and electrically connected to theanode, wherein the ceramic membrane is permeable to alkali metal ions.

In some embodiments of the present disclosure, the alkali metal can besodium. Additionally, the alkali metal-containing solution can be asolution containing an electrolyzible alkali metal containing compound.That electrolyzible alkali metal containing compound can be an alkalimetal with at least one member selected from the group consisting ofchloride, hydroxide, methoxide, alkoxide, tetrafluoroborate, andhexafluorophosphate.

The presently disclosed electrode further includes a power sourceconnected to the anode and cathode. The outside solution can be, amongother things, a solvent or reactant containing solution.

As illustrated in FIG. 1, the present electrode can be made up of aglass, or other suitable material, tube and an alkali metal-containingsolution can be located therein. At the bottom of the tube is a ceramicmembrane which acts as an interface between the alkali metal-containingsolution and the outside solution. Preferably, the ceramic membraneallows alkali ions, like Nat, to pass through while keeping the aqueousbased solution inside the electrode tube. The anode is located insidethe glass tube and immersed in the alkali metal-containing solution,while the cathode located outside the glass tube and immersed in theoutside solution and electrically connected to the anode. Not shown isthe electrical power source located between the electrical connectionbetween the anode and cathode.

Also taught by the present disclosure is an electrochemical processcarried out by providing an electrode comprising a glass tube having analkali metal-containing solution contained therein, a ceramic membranelocated at one end of the glass tube as an interface between the alkalimetal-containing solution and the outside solution, an anode locatedinside the glass tube and immersed in the alkali metal-containingsolution, a power source connected to the anode and cathode, and acathode located outside the glass tube and immersed in the outsidesolution and electrically connected to the anode, decomposing the alkalimetal in the alkali metal-containing solution to form alkali metal ions,passing the alkali metal ions through the ceramic membrane to theoutside solution, reducing the alkali metal ions to alkali metal at thecathode, and reacting the alkali metal with a reactant in the outsidesolution.

This disclosed electrochemical process can have reactants in the outsidesolution that include at least one member selected from the groupconsisting of alcohols, surfactants, fats, acids, amines, oxides,alkoxides, aryloxides, phenoxides, and halocarbons. Various of thesereactants are set forth in more detail below.

The electrochemical process of the present application can furtherinclude the step of isolating the product formed by the step of reactingthe alkali metal with a reactant in the outside solution. In most case,that reactant would be reducible by the alkali metal.

For some embodiments of the electrochemical process, the outsidesolution can be a biological system, or can be a solution that willsubsequently be introduced into a biological system.

As disclosed herein, the electrochemical process can be conducted withsodium as the alkali metal, and, in some of the same or differentembodiments of the electrochemical process the process can be conductedat room temperature.

From large scale use to very small, it would not be difficult to imaginethe use of this process even in a biological system. One applicationcould be based on the human body: the human brain produces 10 W of powermost of which is used to transfer sodium ions, and this is possible inpart due to the differences in the hydration-energy of different ions.For example the sodium ion requires 80 kJ/mol more energy than potassiumto release all of the hydrated water. Given that the membrane propertiesdo not allow water to transfer, this electrochemical system could beused in some form of a dialysis process to regulate sodium content incertain patients. Although several drugs can be found that enable thebody to transfer specific ions across cell membranes and are used in“shock” cases were this transfer is not functioning properly, thepotential for further applications is great.

One example of the presently disclosed process is the conversion ofbenzophenone to the sodium radical at the cathode of the disclosedelectrode. This would be accomplished using a sodium hydroxide solution(or other economically electrolyzible material) on the anode side. Ifthe overpotential is initially too high a small amount of a solublesodium salt such as sodium tetrafluorohorate or hexatluorophosphate canbe added to the outside solution. As long as both sides are not sealed,oxygen and hydrogen production would not yield an additional safetyhazard.

The reduction of organic compounds by sodium metal includes thefollowing typical example, the reaction of sodium metal for sodiumhydride) with an alcohol.

1. 2R−OH+2Na→2RO⁻Na⁺+H₂

Sodium ethoxide, sodium methoxide, sodium propoxide, sodium tea-butoxideare among some of the most commonly made and used alkylates. These areused in a wide range of organic synthesis; agrochemicals;pharmaceuticals; colorants and aromas, detergents, and catalysis.

In order to eliminate the use of sodium metal for the production ofsodium methylate, some producers have developed an electrochemicalprocess using NaCl and methanol. Their process leads to the organictransfer from a sodium salt to another species with an anionic leavinggroup. As mentioned above the sodium alkylates are good examples of thereaction types involving substitution and/or elimination reactions:

or where substitution cannot take place:

Along these same lines, use of the Williamson synthesis would produceunsymmetrical ethers. Aryl alcohols are also frequently used in organicsynthesis, so sodium phenoxide, and other derivative ring systems shouldbe of interest, as reactants in the outside solution of the presentlydisclosed electrode.

Another interest for the pharmaceutical industry is the form of thefinal products. At times drugs are converted to a salt form in order toimprove solubility and transfer within the body, for instance, naproxensodium.

Many processes which use sodium as a metal or a counter-ion are derivedfrom the fact that sodium is a good reducing agent but at times tooreactive and non-selective. There are a few cases where more than onesite on a molecule needs to be reduced. In these cases the reaction isusually run very slowly by addition of very small pieces of sodium.

Other forms of sodium are often used to reduce the rate of reactivityand to increase specificity. Examples include sodium/mercury amalgam,sodium/lead amalgam, and sodium borohydride.

The use of elemental metal and these other reducing agent examples couldbe replaced entirely by this system as one could set the current flowand effectively produce one atom of sodium at a time. Additionallyproduction of extremely reactive species such as NaH or methyl sodium,which is not produced commercially due to its reactivity and shelf lifecould be made in situ as a short-lived intermediate during a process. Afew examples of in situ production include NaH, NaCH₃, or strong baseslike sodium amide.

Another potential in situ process could involve the separation ofenantiomerically pure materials by crystallization. One common counterion for these separations is sodium d-tartrate. As chiral drugs arebecoming more important in the pharmaceutical industry, producing thesalt in situ could give better separation or a greater differentialcrystallization rate.

The presently disclosed method and electrode could also be used toproduce many sodium oxidants, in situ or otherwise, for instance, sodiumsuperoxide, which is used in the inorganic analysis and metal oreisolation.

Some additional sodium-containing compounds that could be produced usingthe presently disclosed method and electrode include dyes, anionicphase-transfer catalysts, and the components needed for two phaseanalysis of surfactants.

In some embodiments of the presently disclosed method, the process couldbe used to produce bromine and chlorine.

In yet further embodiments, the method is utilized in the saponificationstep in the synthesis of soaps and surfactants, as set forthschematically below.

More examples of application of the presently disclosed subject matterare to the production of non-aqueous surfactants and detergents for usein soaps, detergents, lubricating oils, and other technologies. Sodiumalkylbenzene sulfonate, sodium alkyl sulfonate and sodium alkylethoxylates are just a few examples of compounds that can be producedusing the presently disclosed subject matter.

It is known to use NaOH for the removal of naphthalic acid from jetfuel, and it should only be mentioned briefly that the existence ofthese types of long chain and cyclic acids are also found in many otherfuels, and are usually addressed by the addition of detergents to theaffected fuels. Removal of these acids by conversion to the sodium saltand subsequent filtration at the refinery could lead to reduced fueladditives.

Two final areas to which the presently disclosed method and electrodecan be applied include glass manufacturing where the need to controlsodium content can be critical, and also electroplating.

All publications, articles, papers, patents, patent publications, andother references cited, herein are hereby incorporated by referenceherein in their entireties for all purposes.

Although the foregoing description is directed to the preferredembodiments of the present teachings, it is noted that other variationsand modifications will be apparent to those skilled in the art, andwhich may be made without departing from the spirit or scope of thepresent teachings.

The foregoing detailed description of the various embodiments of thepresent teachings has been provided for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit the presentteachings to the precise embodiments disclosed. Many modifications andvariations will be apparent to practitioners skilled in this art. Theembodiments were chosen and described in order to best explain theprinciples of the present teachings and their practical application,thereby enabling others skilled in the art to understand the presentteachings for various embodiments and with various modifications as aresuited to the particular use contemplated. It is intended that the scopeOf the present teachings be defined by the following claims and theirequivalents.

What we claim is:
 1. An electrode comprising a glass tube having analkali metal-containing solution contained therein, a ceramic membranelocated at one end of the glass tube as an interface between the alkalimetal-containing solution and the outside solution, an anode locatedinside the glass tube and immersed in the alkali metal-containingsolution, and a cathode located outside the glass tube and immersed inthe outside solution and electrically connected to the anode, whereinthe ceramic membrane is permeable to alkali metal ions.
 2. The electrodeaccording to claim 1, wherein the alkali metal comprises sodium.
 3. Theelectrode according to claim 1, wherein the alkali metal-containingsolution comprises a solution containing an electrolyzible alkali metalcontaining compound.
 4. The electrode according to claim 3, wherein theelectrolyzible alkali metal containing compound comprises an alkalimetal with at least one member selected from the group consisting ofchloride, hydroxide, methoxide, alkoxide, tetrafluoroborate, andhexafluorophosphate.
 5. The electrode according to claim 1, furthercomprising a power source connected to the anode and cathode.
 6. Theelectrode according to claim 1, wherein the outside solution comprisinga solvent or reactant containing solution.
 7. An electrochemical processcomprising providing an electrode comprising a glass tube having analkali metal-containing solution contained therein, a ceramic membranelocated at one end of the glass tube as an interface between the alkalimetal-containing solution and the outside solution, an anode locatedinside the glass tube and immersed in the alkali metal-containingsolution, a power source connected to the anode and cathode, and acathode located outside the glass tube and immersed in the outsidesolution and electrically connected to the anode, decomposing the alkalimetal in the alkali metal-containing solution to form alkali metal ions,passing the alkali metal ions through the ceramic membrane to theoutside solution, reducing the alkali metal ions to alkali metal at thecathode, and reacting the alkali metal with a reactant in the outsidesolution.
 8. The electrochemical process according to claim 7, whereinthe reactant comprise at least one member selected from the groupconsisting of alcohols, surfactants, fats, acids, amines, oxides,alkoxides, aryloxides, phenoxides, and halocarbons.
 9. Theelectrochemical process according to claim 7, further comprisingisolating the product formed by the step of reacting the alkali metalwith a reactant in the outside solution.
 10. The electrochemical processaccording to claim 7, wherein the outside solution comprises abiological system.
 11. The electrochemical process according to claim 7,wherein the outside solution comprises a reactant reducible by thealkali metal.
 12. The electrochemical process according to claim 7,wherein the alkali metal comprises sodium.
 13. The electrochemicalprocess according to claim 7, wherein the process is conducted at roomtemperature.
 14. An electrochemical process comprising providing anelectrode comprising a glass tube having a sodium metal-containingsolution contained therein, a ceramic membrane located at one end of theglass tube as an interface between the sodium metal-containing solutionand the outside solution, an anode located inside the glass tube andimmersed in the sodium metal-containing solution, a power sourceconnected to the anode and cathode, and a cathode located outside theglass tube and immersed in the outside solution and electricallyconnected to the anode, decomposing the sodium metal in the sodiummetal-containing solution to form sodium ions, passing the sodium ionsthrough the ceramic membrane to the outside solution, reducing thesodium ions to sodium metal at the cathode, and reacting the sodiummetal with a reactant in the outside solution.